Fraunhofer Institute for Production Technology IPTResearchproject "EnablingSapphire"
Challenges of sapphire processing
Sapphire is more than just a gemstone. As a high-performance material, it boasts extreme hardness, chemical resistance, and optical transparency from the ultraviolet (UV) to the infrared spectrum. Sapphire enables applications in quantum technology, high-frequency electronics, and medical technology that would be unthinkable with conventional materials.
However, processing it is challenging. Until now, only simple geometries were feasible. More complex 3D structures are costly to produce and often have quality issues, such as microcracks, surface roughness, and form deviations.
The EnablingSapphire research project aims to address these challenges.
Hybrid manufacturing chain for producing complex components from sapphire
As part of the research project, Fraunhofer IPT and Fraunhofer ILT are developing a digital manufacturing platform to produce complex sapphire components and tools from commercially available semi-finished sapphire products. To achieve this, the researchers are combining laser-based shaping and polishing processes with advanced forming technologies, such as precision glass molding.
Laser-based shaping and polishing
The researchers are investigating the shaping of complex 3D geometries using ultrashort laser pulses. The objective is to fabricate structures featuring undercuts, minimum radii of less than 100 µm, and aspect ratios exceeding 10:1. At the same time, they optimize process parameters, such as beam shaping and thermal pretreatment, to minimize stresses and microcracks.
Another area of focus is laser-based polishing, which achieves low-stress, crack-free surfaces of optical quality. Additionally, surface functionalization processes are being developed, including glassy carbon coatings with and without microstructures, such as refractive or diffractive ones, as well as metallization for conductor tracks. These microstructures will be manufactured using two-photon polymerization combined with a pyrolysis process to create various free-form shapes for the coating.
High-temperature forming using sapphire tools
The team is also investigating sapphire tools for high-temperature forming of challenging glasses, such as borosilicate and quartz, with process temperatures exceeding 1400 °C. In this temperature range, conventional tool materials reach their limits due to wear and dimensional instability. Additionally, targeted surface functionalization, such as glassy carbon coatings, is applied to reduce adhesion, thereby improving demoldability and extending tool lifetime.
Application and validation
The developed process chain is validated using three demonstrators:
- Ion traps for quantum technologies
- Sapphire tools for high-temperature molding of borosilicate and quartz glass optics
- Through-wafer vias for high-performance and high-frequency electronics
These applications demonstrate the platform's potential for a wide range of key technologies.
Funding
The “EnablingSapphire – Digital manufacturing platform for producing complex sapphire components” project is funded by the Fraunhofer internal program PREPARE.
Project partners
- Fraunhofer Institute for Laser Technology ILT (coordination)
- Fraunhofer Institute for Production Technology IPT